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06-10 3.7L Thermostat Info:

B

Best4x4

Well-Known Member
Messages
1,042
Location
Vidor, TX
Okay as some of you may know shortly after I bought my wife's 07 H3 Adventure the radiator blew, and I replaced the thermostat, radiator, water pump, idler pulley, belt tensioner, serpentine belt, and the fan clutch. After all that work my H3's temp's went from the 186-196 range to the 196-213 range. I was worried I had an air bubble in the system (which I did) and I eventually got it out. The temps went down maybe 5F after the bubble was gone, but I was worried about the higher temps vs when I bought it.

The other day I did some looking around on the Colorado Forum's and a lot of people reported the same thing with replacing radiators and thermostats then after their temp's were higher. Well from what I read it appears that GM changed the OEM spec's for our thermostats due to emissions. The OEM units were in fact 180F units originally, but say mid 08 and up they changed them to 190/192 units. Unless you can find some old NOS all the newer thermostats be it aftermarket (auto zone, murray, hayden, stant) or OEM are going to be higher temp thermostats. I did notice that on my 07 before the radiator blew it threw a fault code for not warming up soon enough. Pretty sure the higher temp thermostat solved that issue.

My H3 Adventure runs great and using the scangauge II the temps going 70-80MPH on the freeway are between 200-206F. Stop n go she'll get up to 213, but it cools down quickly and I can hear the fan clutch engaging/disengaging like it should. I just wish with this GM tweak to our thermostat's we could recalibrate our temp gauges! I know it's just an idiot gauge (that's why I have the scangauge II's in both my H3's), but it wouldn't be so scary seeing it above half.

Just thought I'd pass this info along to anyone worried why after some maintenance your temps went up.
 
Airborne

Airborne

Just a regular dude
Messages
294
Location
Utah
Appreciate the info! I ran into a similar prob I'm not sure exactly what I changed or switched but I started running hotter no matter what I did. changed the the thermo twice still dont know what it was... No adverse mileage drop so I'm thinking fan clutch related. any way... I threw in the efan and didn't have to worry about the GM changing things I always knew I wouldn't be running hot. I have hptuners and run a scan about every 3 days and I'm lucky to get ECT above the the 200 mark. Ever. Sitting in traffic or not. I know you have the efan in your alpha... Maybe it's time to free up that I5 a bit??? :)
 
HummerRoller

HummerRoller

Well-Known Member
Messages
149
Location
Schuylkill County, PA
I have an I5 also. Since I purchased it it runs at around 1/4 on the gauge and the CEL comes on. I get the "coolant temperature sensor out of range" code (can't remember the P code off the top og my head.) I just dont want to replace the thermostat and it doesnt go away. We shall see what happens as it gets a bit warmer.

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HummerRoller

HummerRoller

Well-Known Member
Messages
149
Location
Schuylkill County, PA
HummerRoller said:
I have an I5 also. Since I purchased it it runs at around 1/4 on the gauge and the CEL comes on. I get the "coolant temperature sensor out of range" code (can't remember the P code off the top og my head.) I just dont want to replace the thermostat and it doesnt go away. We shall see what happens as it gets a bit warmer. Also mine is an 06.

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B

Best4x4

Well-Known Member
Messages
1,042
Location
Vidor, TX
Yeah I might consider n efan down the road, but 204-206 doesn't bother me 215F + will lol. At least I shouldn't get the fault for temp out of range!

When I first got the Adventure it sat just below half. Then it got cooler due to some cold fronts and it wouldn't go above a 1/4 on the gauge. Changed the thermostat and then the radiator blew lol. Now that I know it's a 190 temp at least I know why it is around 10F hotter.
 
rsc

rsc

Well-Known Member
Messages
1,087
Location
Tulsa
I put an inline thermostat in before the radiator and removed the OEM thermostat. It takes a little longer to warm up and I had to partially block the radiator when it gets down to freezing but when the temps have been up in the 80's the engine temps have been running cooler than last year. I'm waiting for those 100+ days to see how it really performs. If I don't see a big summer difference I'm going back to the OEM piece. Waiting to see...
 
alrock

alrock

El Diablo
Staff member
Messages
10,674
Location
Scottsdale
HummerRoller said:
I have an I5 also. Since I purchased it it runs at around 1/4 on the gauge and the CEL comes on. I get the "coolant temperature sensor out of range" code (can't remember the P code off the top og my head.) I just dont want to replace the thermostat and it doesnt go away. We shall see what happens as it gets a bit warmer.

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Click to expand...
That's pretty much the exact symptoms for a bad thermostat. Not exactly a big gamble to do that fix and I suspect the issue won't go away on its own.
 
B

Best4x4

Well-Known Member
Messages
1,042
Location
Vidor, TX
Yeah once you remove the inner fender liner replacing the thermostat isn't hard at all. Took me around 15m the first time. Then just a refill of coolant.
 
B

Best4x4

Well-Known Member
Messages
1,042
Location
Vidor, TX
With the warmer stat it shouldn't throw that fault code for not warming up in time, and apparently GM found it better on emissions enough to change it to a 190. Going to leave mine as is for now.
 
digglesworth

digglesworth

Well-Known Member
Messages
1,789
Location
illinois
HummerRoller said:
I have an I5 also. Since I purchased it it runs at around 1/4 on the gauge and the CEL comes on. I get the "coolant temperature sensor out of range" code (can't remember the P code off the top og my head.) I just dont want to replace the thermostat and it doesnt go away. We shall see what happens as it gets a bit warmer.

Sent from my SAMSUNG-SGH-I317 using Tapatalk
Click to expand...

Mine did the same thing when I bought it in the summer. As fall hit (cooler temps) I started getting the p0128. Replaced the thermostat with an oem ac delco and it solved the problem. Temp gauge sits just above 1/2. Scangauge reads 198-202 all the time. It's a little bit of a pain but it's a cheap fix and couldn't hurt your truck to freshen up the cooling system. Get that snotty old dex-cool replaced with some new stuff.
 
H

Hicksy712

Member
Messages
15
Location
Nashville
Bought mine back in oct of 13'. The whole time I just thought the heater in these things sucked. Finally got a code and radiator split. Replaced all including pump and fixed as described above.
 
Pappibri

Pappibri

Well-Known Member
Messages
1,611
Location
Cohoctah, MI
I had a cracked radiator replaced by the GM dealer last year, and every since then it has run hotter. It always ran between a 1/4 and 1/2 on the gauge, now it always runs at half and above. No problems or worries about it though.
 
amrg

amrg

Well-Known Member
Messages
2,317
Location
Qatar
Reading through this thread, Is there a suitable 180* replacement thermostat for the Alpha? I've noticed that my ECT goes up to 215* in the summer and thats with 2 electric fans + the clutch fan (thats during wheeling) but Im reading around 200* during normal use. I've had my coolant flushed couple of months back and changed the thermos back then, now its the middle of the summer and my truck feels sluggish from all the heat and I'm sure it didn't feel like this last summer. I know I read on a colorado forum someone changed to 170* T-stats, would that work here?

This is a part# I got for a 180* T-stat, is this a proper replacement for our trucks?

http://www.ebay.com/itm/Engine-Cool...Parts_Accessories&vxp=mtr&hash=item1c3b7ce312
 
hummer7

hummer7

Probationary Member
Messages
4
Location
Gulf Coast on the Alabama - Florida line
Best4x4 said:
Okay as some of you may know shortly after I bought my wife's 07 H3 Adventure the radiator blew, and I replaced the thermostat, radiator, water pump, idler pulley, belt tensioner, serpentine belt, and the fan clutch. After all that work my H3's temp's went from the 186-196 range to the 196-213 range. I was worried I had an air bubble in the system (which I did) and I eventually got it out. The temps went down maybe 5F after the bubble was gone, but I was worried about the higher temps vs when I bought it.

The other day I did some looking around on the Colorado Forum's and a lot of people reported the same thing with replacing radiators and thermostats then after their temp's were higher. Well from what I read it appears that GM changed the OEM spec's for our thermostats due to emissions. The OEM units were in fact 180F units originally, but say mid 08 and up they changed them to 190/192 units. Unless you can find some old NOS all the newer thermostats be it aftermarket (auto zone, murray, hayden, stant) or OEM are going to be higher temp thermostats. I did notice that on my 07 before the radiator blew it threw a fault code for not warming up soon enough. Pretty sure the higher temp thermostat solved that issue.

My H3 Adventure runs great and using the scangauge II the temps going 70-80MPH on the freeway are between 200-206F. Stop n go she'll get up to 213, but it cools down quickly and I can hear the fan clutch engaging/disengaging like it should. I just wish with this GM tweak to our thermostat's we could recalibrate our temp gauges! I know it's just an idiot gauge (that's why I have the scangauge II's in both my H3's), but it wouldn't be so scary seeing it above half.

Just thought I'd pass this info along to anyone worried why after some maintenance your temps went up.
Click to expand...


I just replaced my thermostat because of the code implying my thermostat was going bad. and my AC off light coming on... as long with a new cylinder head from number 5 random misfire... $2800.00
I have a 2008 I5 with only 64,000 My temp was alwasy at the 1/4 mk to almost the 1/2 mk. Now my temp is at the 1/2 mk to 1/2.1 tick should I be concerned about the higher temps? I live on the gulf coast where its very hot!
 
alrock

alrock

El Diablo
Staff member
Messages
10,674
Location
Scottsdale
Sounds like your thermostat was stuck open, which is why your temps were below 1/2. It's now in the normal range

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